1. Field of the Invention
The present invention relates to a gas exhaust structure of a battery, which is capable of instantaneously exhausting, to an outside, gas that abruptly spouts out from an inside of a battery by an impact applied from the outside.
2. Description of the Related Art
In recent years, as one of drive sources for driving a vehicle such as an electric vehicle and a hybrid vehicle, a battery that is a secondary battery has been used gradually and increasingly. As such a battery for the vehicle drive source, there is one configured as one battery column formed by stacking (serially connecting) a large number of unitized batteries on one another. Such formation of the battery column facilitates handling of a large number of the batteries, and in addition, makes it possible to obtain a high voltage for the vehicle drive source.
Incidentally, when a large external impact is applied to the battery owing to an accident and the like in the case where such a battery column is used while being mounted on the vehicle, a large amount of combustible gas such as hydrogen abruptly spouts out from the battery, which composes the battery column, in response to this impact application. Then, it is apprehended that the battery may explode unless the spouting gas from the battery is relieved. It is said that an internal pressure of the battery at this time rises to approximately 7 atmospheric pressures.
In order to prevent such a situation, the battery includes a gas exhaust structure for instantaneously exhausting such high-pressure gas to an outside (Japanese Patent Laid-Open Publication No. 2002-216731 as Patent Publication 1).
FIGS. 1A and 1B are views for explaining the conventional gas exhaust structure of the battery.
As shown in FIGS. 1A and 1B, a unitized battery A includes a battery body 1, positive and negative electrodes 2 and 3, and a pipe unit 4. The positive and negative electrodes 2 and 3 are individually provided on both end portions of an upper portion 1a of the battery body 1. Moreover, on a portion of the upper portion 1a, which is located between the positive and negative electrodes 2 and 3, an incision is incised. Then, this incision is broken from an inside of the body 1 at the time when the gas spouts, and forms a rupture valve 1b. Once the rupture valve 1b is formed as described above, it becomes impossible to reuse the battery A.
The pipe unit 4 as a coupling pipe unit instantaneously guides the gas, which spouts out from the inside of the battery body 1 through the rupture valve 1b, to an outside of the battery body 1, and then exhausts the gas thereto. The pipe unit 4 is composed by integrating an exhaust pipe 4a and a coupling pipe 4b with each other. The coupling pipe 4b coupled to the rupture valve 1b is coupled to the exhaust pipe 4a. 
In such a way, when a large number of the batteries A, each of which has the above-described configuration, are stacked on one another, the respective exhaust pipes 4a are sequentially fitted and coupled to one another, and form one gas exhaust passage of the battery column.